Electric arc cutting and welding torches are well known in the art. Such devices as commonly used on the surface are adapted for underwater use in the salvaging of sunken vessels and drill platforms; repairing ships, and in the construction and maintenance of subsea structures.
Cutting Torches as presently used underwater, have particularly severe problems in cutting nonferrous metals, stainless steels and nonconductive substances such as cement, concrete, bitumens, barnacles and other marine growth. Maintaining a continuous arc underwater, at any depth, is impossible when the material to be cut is non-conductive. The present generation of arc cutting rods will not penetrate or cut through non-conductive materials. Present arc-oxygen systems cannot function without a power source. Where the power is removed, the arc extinguishes itself, and the rod will not sustain itself in burning. Available arc-oxygen units cannot cut through non-conductive materials.
The arc-oxygen method of cutting metals is based on the same principle as that employed in oxy-acetylene cutting. In the latter, the metal is first locally preheated to incandescence by means of the oxy-acetylene flame. When incandescence is reached, a high velocity jet of oxygen is impinged upon the preheated spot. The oxygen jet performs the double duty of oxidizing or burning the core of the preheated portion and removing the products of combustion. The oxy-acetylene flame continuously advances the incandescent spot in preparation for the action of the oxygen stream. In arc-oxygen cutting, preheating is performed by the electric arc maintained between the material being cut and the electrode. Since the heat energy available in an arc is much greater than that of an oxy-acetylene flame, preheating with the arc-oxygen method is practically instantaneous. Therefore, the instant the arc is struck, the high velocity oxygen stream is admitted to impinge upon the preheated spot where the same phenomena occur as given for the oxy-acetylene cutting. Advancing the electrode along the intended line of cut while the electric arc is continuously maintained, results in the uninterrupted succession of preheat, oxidation and removal of the burned metal.